The majority of all parasympathetic fibers are from what cranial nerve?

The majority of the parasympathetic outflow from the head is by the vagus nerve.

What is Cranial Nerve XI called, and what does it do?

XI: ACCESSORY NERVE enters the skull through foramen magnum and leaves through the jugular foramen. It just supplies the shoulder muscles.

What is Cranial Nerve XII called, and what does it do?

XII. HYPOGLOSSAL NERVE (hypo=under; glossal=tongue) - supplies the under surface of the tongue.

What does damage to this nerve cause?

Damage causes impairment of speech.

Where does spinal cord begin and end?

FORAMEN MAGNUM. It goes to L1-2.

In infants, it ends at L4-5, because it doesn't grow as fast as the rest of the body.

What is the spinal cord called beyond L1-2?

CAUDA EQUINA ("Horse's tail"), which exit through the intervertebral foramina.

Where does the SACRAL PLEXUS exit the spinal cord?

The SACRAL PLEXUS is made up of the spinal nerves exiting the spinal cord from the level of L4 to S5.

What spinal nerve has a number that does not correspond to a vertebra?

There is a spinal nerve C8, although there is no C8 vertebrae.

Define a GANGLION (plural is ganglia)

Ganglion = a group of neuron cell bodies.Some are motor, some are sensory.

Are they motor or sensory?

The ganglia in the dorsal root are always sensory.

Are they in the CNS, PNS, or both?

All ganglia are in the PNS only

Where are the cell bodies of the sensory neurons of the spinal nerves located?

Posterior root ganglion

Most synapses are in what part of the nervous system?

Most synapses are in the CNS

Define SENSORY NEURONS:Where do they come in to the spinal cord?Where is their cell bodyWhere do they synapseWhat pathway do they take to the brainIn what part of the brain do they terminate?

SENSORY NEURONS come in through the posterior root, their cell body is in the posterior root ganglion, and its axon goes into the posterior horn and synapses in the grey matter.

It also sends a branch to an area of the white matter called the DORSAL COLUMN PATHWAY, which goes into the brain (thalamus).

Axons in the DORSAL COLUMN PATHWAY go to what part of the brain?

Thalamus

Define LOWER MOTOR NEURONS:Where is their cell bodyWhere does their axon exit the spinal cordWhere do they synapse

LMN's have their cell body in the anterior horn (of the gray matter), and their axon goes out the anterior root, and synapses in a muscle.

Define INTERNEURONS:Where are their cell bodiesWhere do they synapseWhat is another name for them?

Their cell bodies are in the dorsal half of the gray matter in the spinal cord.

They receive signals from the sensory neuron and then synapse on the cell body of the motor neuron. In this way, the interneurons (sometimes called association neurons) transmit signals from the sensory pathways to the motor pathways.

The complexity of the CNS can be attributed to what?

The complexity of the CNS can be attributed to Interneurons

What types of sensory information are conveyed toward the brain in the spinothalamic tracts?

Pain and temperature

What are the 3 nerves that form a simple reflex arc?

Sensory, lower motor, and interneuron forms the SIMPLE REFLEX ARC.

Example of a withdrawal reflex.

If you touch a hot stove, the sensory input comes into the spinal cord, the association neurons send the information to the lower motor neurons, the muscle contracts, and you take your hand off the stove before your brain even knows it.